A sorting apparatus is configured to sort defective workpieces failing to satisfy predetermined conditions and remove the defective workpieces. Such a sorting apparatus includes a conveying apparatus for conveying workpieces from a supplying mechanism to a detection region.
As an example of the sorting apparatus including a conveying apparatus, FIG. 11 illustrates a sorting apparatus 301 described in Japanese Unexamined Patent Application Publication No. 2012-55859.
In the sorting apparatus 301 in Japanese Unexamined Patent Application Publication No. 2012-55859, workpieces W, which include non-defective workpieces GW and defective workpieces NW, are conveyed from a supplying mechanism 302 to a detection region 303.
The workpieces W are conveyed by a conveying apparatus that includes a conveyer belt 304 and a slide 305 for guiding the workpieces W supplied from the supplying mechanism 302 to the conveyer belt 304.
A vibration mechanism, which is not illustrated, is attached to the slide 305. When the vibration mechanism vibrates the slide 305, the workpieces W travel on the slide 305 to a front end portion of the conveyer belt 304.
The workpieces W are conveyed at a predetermined speed from the front end portion to the rear end portion of the conveyer belt 304 due to travel of the belt.
The workpieces W arriving at the rear end portion of the conveyer belt 304 are discharged into the detection region 303 in accordance with the momentum gained while the workpieces W are conveyed by the conveyer belt 304. The detection region 303 is a space defined between an irradiation source 303a, which applies electromagnetic waves such as visible light or X-ray to the workpieces W, and a receiver 303b. 
The electromagnetic waves received by the receiver 303b vary depending on the condition of the workpieces W passing through the detection region 303. The workpieces W are each determined as a non-defective workpiece GW or a defective workpiece NW based on the information of the electromagnetic waves received by the receiver 303b. 
In the sorting apparatus 301 in Japanese Unexamined Patent Application Publication No. 2012-55859, the workpieces W are supplied consecutively by the supplying mechanism 302, but the positions of the workpieces W are not adjusted. Thus, the workpieces W may overlap each other on the slide 305 or on the conveyer belt 304.
In such a case, the electromagnetic waves may not be evenly applied to each of the overlapped workpieces W discharged into the detection region 303. This results in inaccurate sorting of the non-defective workpieces GW and the defective workpieces NW.
The above-described problem, which occurs when the overlapped workpieces W are conveyed, may occur on an apparatus other than the sorting apparatus for sorting the non-defective workpieces GW and the defective workpieces NW by applying the electromagnetic waves as described in Japanese Unexamined Patent Application Publication No. 2012-55859.
Workpieces may overlap each other in a sorting apparatus configured to sort defective workpieces by checking the appearance of the workpieces with a camera while the workpieces are conveyed. In such a case, the overlapped parts of the workpieces are not visible. This results in inaccurate sorting of the non-defective workpieces and the defective workpieces.
Workpieces, which include a semi-cured light-curable resin member, may overlap each other in a curing apparatus for curing resin by applying light having a predetermined wavelength to the workpieces being conveyed. In such a case, light may not be applied to the overlapped parts of the workpieces. This results in uneven curing of the resin.
Workpieces may overlap each other in a heat treatment apparatus for heating workpiece members, which are temporally fixed to each other with a thermosetting resin or solder, by using an infrared heater while conveying the workpiece to fix the members to each other. In such a case, the overlapped workpieces may be unevenly heated. This results in uneven fixation strength of the members.